Adjustable wing plow

ABSTRACT

A plow assembly includes a pair of plow wings which are pivotally mounted at opposite ends of a center plow. Each of the plow wings may pivot between a forwardly angled position and an aligned position. The plow assembly may pivot a trailing plow wing in response to the center plow being urged or angled toward that side of the vehicle. The plow wines may be oriented in their forwardly angled position until the center plow is at least substantially urged or pivoted toward its angled position or toward a position between the center position and the angled position. The trailing plow wing may be pivoted or urged to its aligned position in response to the center plow being substantially urged or pivoted toward its angled position or toward a position between its center position and its angled position.

CROSS REFERENCE TO RELATED APPLICATION

The present application claims benefit of U.S. provisional application,Ser. No. 60/467,712, filed May 2, 2003, which is hereby incorporatedherein by reference in its entirety.

FIELD OF THE INVENTION

The present invention relates generally to plow assemblies for mountingto a vehicle and for pushing or moving snow, dirt, sand, gravel and/orother plowable material and, more particularly, to a plow assemblyhaving plow wings which are adjustable between a straight or alignedposition generally parallel to a main or center mold board or plow ofthe plow assembly and a forwardly angled position for limiting theplowed material from slipping off the ends of the main or center plow ofthe plow assembly.

BACKGROUND OF THE INVENTION

It is known to provide pivotable plow wings at one or both ends of amain plow of a plow assembly for a vehicle. Examples of such plowassemblies are shown in U.S. Pat. Nos. 6,408,549; 6,442,877; and6,412,199, which are hereby incorporated herein by reference. The plowwings may be adjustable via actuation of corresponding actuators and maybe adjustable independently of a position or orientation of the main orcenter plow. It is also known to provide a plow assembly with plow wingswhich each move between a forwardly angled position, where the plow wingis angled forwardly from the main plow, and an aligned position, wherethe plow wing is generally aligned with the main plow. The plow wingsmay pivot between their positions in response to pivotal movement of themain plow relative to the vehicle. Such a snowplow assembly is disclosedin U.S. Pat. No. 3,477,151, issued to Zanella on Nov. 11, 1969.

SUMMARY OF THE INVENTION

The present invention is intended to provide a plow assembly withpivotable and adjustable plow wings at opposite ends of a main or centerplow. The plow wings are adjustable between a forwardly angled positionand a generally aligned position relative to the center plow. Each plowwing may be pivotable in response to the center plow being pivotedtoward the side of the respective plow wing. The plow wings may bebiased toward their forwardly angled positions and may only move totheir generally aligned position when the center plow has been fully orsubstantially or at least partially pivoted toward the side of therespective plow wing.

According to an aspect of the present invention, a plow assembly for avehicle includes a center plow having first and second ends, a supportfor attaching the plow assembly to the vehicle, first and second plowwings and a wing pivoting system. The center plow is pivotable relativeto the vehicle between a first position, where the center plow ispivoted toward the first end, and a second position, where the centerplow is pivoted toward the second end. Each of the first and second plowwings is pivotally mounted at a respective one of first and second endsof the center plow and is pivotable between an angled position, wherethe plow wing is angled forwardly with respect to the center plow, andan aligned position, where the plow wing is generally aligned with thecenter plow. The first and second plow wings are biased toward theangled positions via at least one biasing member. The wing pivotingsystem is operable to pivot the first plow wing toward the alignedposition in response to the center plow being pivoted toward the firstposition, and to pivot the second plow wing toward the aligned positionin response to the center plow being pivoted toward the second position.The wing pivoting system includes at least one connecting member whichis connected to the first and second plow wings and to the support. Theconnecting member or members is/are configured to move the first plowwing toward the aligned position as the center plow is pivoted towardthe first position and to allow the first plow wing to move toward theangled position in response to the biasing member as the center plow ispivoted away from the first position. Likewise the connecting member ormembers is/are configured to move the second plow wing toward thealigned position as the center plow is pivoted toward the secondposition and to allow the second plow wing to move toward the angledposition in response to the biasing member as the center plow is pivotedaway from the second position.

The at least one connecting member may comprise at least one cableconnected to the first and second plow wings and to the support. Thecable may connect to a lever arm at each of the first and second plowwings to pivot at least one of the lever arms relative to the centerplow to correspondingly pivot the respective plow wing, such as via aconnecting linkage connected between the lever arm and the plow wing.The cable may move outwardly relative to the lever arm to allow therespective plow wing to pivot toward the angled position in response tothe at least one biasing member when the center plow is pivoted awayfrom its first or second position.

According to another aspect of the present invention, a plow assemblyfor a vehicle includes a center plow, a support for attaching the centerplow to the vehicle, a first plow wing on the first end of the centerplow and a second plow wing on the second end of the center plow. Thecenter plow is pivotable relative to the vehicle between a firstposition, where the center plow is pivoted toward the first end, and asecond position, where the center plow is pivoted toward the second end.Each of the plow wings is pivotally mounted to a respective one of theends of the center plow and is pivotable between an angled position,where the plow wino is angled forwardly with respect to the center plow,and an aligned position, where the plow wing is generally aligned withthe center plow. A first biasing member is connected between the mainplow and the first plow wing and a second biasing member is connectedbetween the main plow and the second plow wing. Each of the biasingmembers is selectively mounted at the main plow and/or the plow wing inone of at least two mounting positions. The biasing member isselectively mounted in a first mounting position to position therespective plow wing in the aligned position and in a second mountingposition to position the respective plow wing in the angled position.The biasing members is compressible to absorb an impact of therespective plow wing with an object during operation of the plowassembly.

According to another aspect of the present invention, a plow assemblyfor a vehicle includes a center plow having first and second ends, asupport for attaching the plow assembly to the vehicle, a first plowwing at the first end of the center plow, and an actuating or wingpivoting system. The center plow is pivotable relative to the vehiclebetween a first position, where the center plow is angled toward thefirst end, and a center position, where the center plow is positionedgenerally normal to the direction of travel of the vehicle. The firstplow wing is pivotally mounted at the first end of the center plow andis pivotable between an angled position, where the plow wing is angledforwardly with respect to the center plow, and an aligned position,where the plow wing is generally aligned with the center plow. Theactuating system is operable to urge the first plow wing toward theangled position until the center plow is urged at least substantiallytoward one of the first position and a position between the first andcenter positions. The actuating system urges the first plow wing towardthe aligned position in response to the center plow being urged at leastsubstantially toward the first position or the position between thefirst and center positions.

The plow assembly may include a second plow wing at the second end ofthe center plow. The actuating system may also be operable to pivot thesecond plow wing to its aligned position in response to the center plowbeing at least substantially urged toward a second position (where thecenter plow is pivoted toward the second end) or a position between thesecond and center positions. The actuating system may also urge each ofthe plow wings toward their angled positions in response to the centerplow being at least partially urged toward the opposite side.

The actuating system may comprise a hydraulic system that includes atleast one plow actuator for urging or pivoting the center plow to thefirst and second positions, and first and second wing actuators forurging or pivoting the first and second plow wings, respectively,relative to the center plow. The first and second wing actuators may bebiased to bias the plow wings toward their angled positions. The wingactuators may be biased via a biasing pressure within the actuatorswhich is greater than a fluid pressure applied to the plow actuators tourge or pivot the center plow between the first and second positions.The biasing pressure at the first or second wing actuator may beovercome as the pressure at a corresponding one of plow actuatorsincreases as the center plow is urged or pivoted at least substantiallytoward its first or second position.

According to another aspect of the present invention, a plow assemblyfor a vehicle includes a center plow having first and second ends, asupport for attaching the center plow to the vehicle, a first plow wingpivotally mounted to the first end of the center plow, and an actuatingsystem. The center plow is pivotable relative to the vehicle between afirst position, where the center plow is pivoted toward the first end,and a center position, wherein the center plow is positioned generallynormal to the direction of travel of the vehicle. The first plow wing ispivotable between an angled position, where the first plow wing isangled forwardly with respect to the center plow, and an alignedposition, where the first plow wing is generally aligned with the centerplow. The actuating system comprises at least one plow actuator operableto pivot the center plow between the first and center positions and afirst wing actuator operable to pivot the first plow wing between theangled and aligned positions.

In one form, the plow actuator is operable to urge the center plowtoward the first position in response to a first pressure being appliedto the plow actuator, while the first wing actuator is operable to urgethe first plow wing toward the aligned position in response to a secondpressure being applied to the first wing actuator. The first pressure isless than the second pressure, such that the center plow is at leastsubstantially urged toward the first position or a position between thefirst and center positions before the first plow wing is urged towardthe aligned position.

In another form, the first wing actuator is operable to urge the firstplow wing toward the aligned position in response to a first pressurebeing applied to the first wing actuator, while the plow actuator isoperable to urge the center plow toward the first position in responseto a second pressure being applied to the plow actuator. The firstpressure is less that the second pressure, such that the first plow wingis at least substantially urged toward the aligned position before thecenter plow is urged toward the first position.

According to yet another aspect of the present invention, a plowassembly for a vehicle includes a center plow having first and secondends, and a first plow wing on the first end of the center plow. Thecenter plow is mountable to the vehicle and is pivotable relative to thevehicle between a first position where the center plow is pivoted towardthe first end, and a center position, where the center plow ispositioned generally normal to the direction of travel of the vehicle.The first plow wing is pivotally mounted to the first end of the centerplow and is pivotable between an angled position, where the first plowwing is angled forwardly with respect to the center plow, and an alignedposition, where the first plow wing is generally aligned with the centerplow. The first plow wing is biased toward the angled position and ispivotable toward the aligned position in response to a load against thefirst plow wing in a direction generally along the center plow at leastwhen the center plow is angled toward the first position.

Therefore, the present invention provides a plow assembly with pivotableplow wings which are pivotable in response to a pivotal movement of amain or center plow toward one side or the other. The trailing plow wing(or the plow wing which is at the end of the center plow toward whichthe center plow is pivoted or angled) may pivot toward and to itsaligned position after the center plow has been pivoted or urged atleast partially or substantially toward its fully angled or pivotedposition, such that both of the plow wings may remain in their forwardlyangled positions throughout most of the pivotable range of motion of thecenter plow. The plow wings may be biased toward their angled positions,in order to maintain the plow wings in their angled positions until thebiasing force exerted on the trailing plow wing is overcome as thecenter plow pivots to the respective sidewardly angled or pivotedposition. The plow wings may pivot in response to a cable pulling at aportion of the plow wings and pulling against the biasing force exertedat the plow wings to pivot the respective plow wing toward its alignedposition as the center plow pivots or angles toward the respective plowwing. Optionally, the trailing plow wing may pivot toward its alignedposition in response to initial pivoting or urging of the center plow orin response to actuation of an actuating system of the plow assembly,such that the plow wing pivots to its generally aligned position beforesubstantial pivotal movement of the center plow occurs. The actuatorsfor pivoting the plow wings may be operable in response to lesshydraulic fluid or less hydraulic pressure than the plow actuators forpivoting the center plow, such that each plow wing may move or pivot toits aligned position before the center plow moves or pivots toward therespective sidewardly angled or pivoted position.

These and other objects, advantages, purposes and features of thepresent invention will become apparent upon review of the followingspecification in conjunction with the drawings.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a rear perspective view of a plow assembly in accordance withthe present invention, with the plow assembly being mountable to avehicle via an A-frame support;

FIG. 2 is a rear elevation of the plow assembly of FIG. 1, with theA-frame support removed therefrom, and with the left plow wing pivotedtoward its generally aligned orientation;

FIG. 3 is a rear elevation of the plow assembly of FIG. 1, with bothplow wings angled toward their forwardly angled position;

FIG. 4 is a partial sectional view of the plow assembly taken along theline A-A in FIG. 3;

FIG. 5 is another rear elevation of the plow assembly similar to FIG. 3,with the center plow angled toward the left side with respect to theA-frame support, and with the left plow wing pivoted toward itsgenerally aligned orientation;

FIG. 6 is a partial sectional view of the plow assembly taken along theline B-B in FIG. 5;

FIG. 7 is a side elevation of a biasing member or rod useful with theplow assembly of FIGS. 1-6;

FIG. 8 is a perspective view of the front of the plow assembly of FIGS.1-6;

FIG. 9 is a top plan view of another plow assembly in accordance withthe present invention, with the plow angled toward one side and theleading plow wing in its forwardly angled position;

FIG. 10 is a perspective view of the cable and linkages at one side ofthe plow assembly of FIG. 9;

FIG. 11 is a side elevation and partial sectional view of a hydraulicspring and damper assembly useful with the plow assembly of FIGS. 9 and10;

FIG. 12 is a top plan and partial sectional view of another plowassembly in accordance with the present invention;

FIG. 13 is a rear elevation of another plow assembly in accordance withthe present invention;

FIG. 14 is a top plan view of another plow assembly in accordance withthe present invention, with the plow wings being manually set at theirgenerally aligned position or forwardly angled position;

FIG. 15 is a rear perspective view of another plow assembly inaccordance with the present invention, with the plow wings beingpivotable via respective actuators;

FIG. 16 is a rear elevation of the plow assembly of FIG. 15, with theright plow wing pivoted toward its generally aligned orientation;

FIG. 17 is a partial sectional view of the plow assembly taken along theline C-C in FIG. 16;

FIG. 18 is an exploded perspective view of the rear of the plow assemblyof FIGS. 15-17, with the left plow wing removed from the main plow;

FIG. 19 is a perspective view of the front and side of the plow assemblyof FIGS. 15-18;

FIG. 20 is a hydraulic schematic of a hydraulic actuating systemsuitable for use with the plow assembly of the present invention;

FIG. 21 is a hydraulic schematic of another hydraulic actuating systemsuitable for use with the plow assembly of the present invention;

FIG. 22 is a hydraulic schematic of another hydraulic actuating systemsuitable for use with the plow assembly of the present invention;

FIG. 23 is a hydraulic schematic of another hydraulic actuating systemsuitable for use with the plow assembly of the present invention;

FIG. 24 is a sectional view of a plow actuator useful with the hydraulicactuating system of FIG. 23; and

FIG. 25 is a hydraulic schematic of another hydraulic actuating systemsuitable for use with the plow assembly of the present invention.

DESCRIPTION OF THE PREFERRED EMBODIMENTS

Referring now specifically to the drawings and the illustrativeembodiments depicted therein, a plow assembly 10 is mounted to a pushbeam or the like (not shown) on a vehicle (also not shown) via a support12, such as an A-frame support or the like (FIG, 1). Plow assembly 10may be mounted to support 12 via an intermediate support 15 at a rearportion of a main or center plow 14 of plow assembly 10. Intermediatesupport 15 may be pivotally mounted to support 12 and may be pivotabletoward one side or the other about a generally vertical pivot axis 12 a,while support 12 may be pivotally mounted to the push beam assembly andmay be pivotable about a generally horizontal axis 12 b to raise orlower the plow with respect to the vehicle. Plow assembly 10 includesopposite plow wings 16, 18 pivotally mounted at opposite ends of thecenter plow 14. Plow assembly 10 also includes a wing pivoting system oractuating system 22, which is operable to pivot one or both of the plowwings 16, 18 relative to center plow 14 in response to pivoting ofcenter plow 14 about pivot axis 12 a, as discussed below,

As best shown in FIGS. 1 and 8, main or center plow 14 may include amain curved mold board or material engaging surface 14 a and a plowblade 14 b for pushing or plowing snow, dirt, sand, gravel and/or otherplowable material as the center plow 14 is moved through the snow orother material by the vehicle. Center plow 14 may also include mountingbracket or intermediate support 15 for pivotally mounting center plow 14to a forward end of support 12.

Plow assembly 10 may be mounted to a push beam assembly of any vehicle,such as a pickup truck or the like, via support 12. The plow assembly 10may be pivotable toward the right or left side of the vehicle, such asvia a pair of plow angling actuators 20 a, 20 b, such as hydrauliccylinders or the like, which may correspondingly extend and retract topivot the main or center plow about vertical pivot axis 12 a at aforward end 12 c (FIGS. 4 and 6) of support 12. As center plow 14 pivotstoward one side of the support 12 and the vehicle, such as toward theleft side as shown in FIG. 1, the wing pivoting device or system 22 maybe operable to pivot the trailing plow wing, such as the left plow wing16 in FIG. 1, toward its generally aligned position in response tocenter plow 14 pivoting toward that side of the vehicle, as discussedbelow.

Support frame 12 may be any type of support frame or mounting means,such as the A-frame support of the illustrated embodiment or such asknown or conventional mounting arms, frames or supports or the like,without affecting the scope of the present invention. As shown in FIG.1, support frame 12 may be of the type suitable for attachment to a pushbeam or the like at a front of a pickup truck or the like, and mayinclude a triangular-shaped or A-frame shaped reinforced frame workhaving a base 12 d and inwardly tapering sides 12 e and spaced pairs ofrearwardly extending support flanges 12 f on base 12 d. The supportflanges 12 f may be configured and arranged to allow support 12 to besecured to a suitable hitch assembly or the like on the front of apickup truck or other vehicle, while allowing pivotal movement ofsupport 12, and thus of the plow assembly, about horizontal pivot axis12 b extending through the support flanges 12 f. Plow angling actuators20 a, 20 b may mount at opposite ends of base 12 d and extend forwardlyto connect to the mounting bracket or intermediate support 15 of plowassembly 10. Extension of one actuator, such as the right actuator 20 bin FIG. 1, and a corresponding retraction of the other hydrauliccylinder or actuator at the other side of support 12, causes pivotalmovement of the intermediate support 15 and the main or center plow 14about pivot axis 12 a at the forward end 12 c of support 12.

As can be seen in FIGS. 4 and 6, support 12 includes the forward end orforwardly projecting portion 12 c, which extends forwardly from pivotaxis 12 a. When center plow 14 is pivoted, forwardly projecting portion12 c may move or pivot toward the opposite side of the plow assemblyfrom the side toward which the center plow is pivoted relative tosupport 12. The side to side movement of forwardly projecting portion 12c may function to move or drive or actuate the wing pivoting oradjusting device or system 22 as center or main plow 14 and intermediatesupport 15 are pivoted about pivot axis 12 a relative to support 12, asdiscussed below.

Each plow wing 16, 18 may be pivotally mounted at a respective end ofcenter plow 14 via a hinge or pivot axle 24. Plow wings 16, 18 arepivotable about their respective hinges 24 between their forwardlyextended or angled positions (such as right plow wing 18 is shown inFIG. 1), and their generally aligned positions (such as left plow wing16 is shown in FIG. 1). The plow wings 16, 18 may each include a curvedmaterial engaging surface or partial mold board 16 a, 18 a (FIGS. 1 and8) for pushing the plowed material as plow assembly 40 is moved throughthe material by the vehicle. The partial mold boards 16 a, 18 amaypartially overlap the mold board 14 a of center plow 14, and may havecurved inner edges 16 b, 18 b (FIG. 8), such that center plow 14 andplow wings 16, 18 maintain a generally uniform and continuous materialengaging surface irrespective of the position or orientation of eitherof the plow wings relative to the center plow. As can be seen in FIG. 4,the hinges 24 may be positioned generally rearward of the materialengaging surfaces 16 a, 18 a, 14 a of the plow wings 16, 18 and centerplow 14 so as to provide a substantially continuous plow surface. Eachof the plow wings 16, 18 may also include a plow blade 16 c, 18 c (FIG.8) along the lower edge of the wings.

When center plow 14 is in a generally straight or non-angled or centerposition, where the main or center plow is positioned generally normalto the direction of travel of the vehicle, both plow wings 16, 18 may bepositioned in or biased toward their forwardly angled position, suchthat plow assembly 10 may form or define a generally U-shaped materialengaging surface for pushing and carrying snow or other material as plowassembly 10 is moved through the snow or other material being plowed.When center plow 14 is angled toward one side of the vehicle, the plowwing that is toward the side of the vehicle or plow assembly towardwhich the center plow is angling (i.e. the trailing plow wing) may bepivoted to the generally aligned position or orientation in response towing pivoting system 22, while the other plow wing (i.e. the leadingplow wing) remains in the generally forwardly angled position. Theangles of the plow wings at their forwardly angled positions may beselected such that when the center plow is tilted or angled toward itsfully angled or tilted position toward one side of the vehicle, theleading plow wing (the plow wing at the end of the main plow which isopposite from the end toward which the main plow is angled) may beoriented generally along the direction of travel of the vehicle when inits forwardly angled position.

Plow wing pivoting system 22 may include one or more cables 26 which areconnected at forwardly extending portion 12 c of support 12 and whichare movable in response to pivotal movement of center plow 14 aboutpivot axis 12 a, in order to pull a respective plow wing toward itsaligned position, as discussed below. As best shown in FIGS. 2, 4 and 6,cables 26 may be pivotally mounted at forward extending portion 12 c ofsupport 12 and may extend laterally outwardly therefrom and through abushing or the like 15 a at intermediate support or bracket 15. An outerend 26 a of each cable 26 may be slidably received through an outer endof a lever or pivot arm 28 (or between spaced apart pivot arms 28 asshown in the illustrated embodiment). Pivot arm or arms 28 may bepivotally mounted at a rear portion of center plow 14, such as via apin, bolt or fastener 17 a at a mounting portion or bracket 17 b ofcenter plow 14, and may extend rearwardly therefrom. As best shown inFIGS. 1, 4 and 6, each pivot arm 28 (such as each pair of spaced apartpivot arms) may be pivotally connected to a plow wing connecting link 30and a main plow connecting link or pair of spaced connecting links 32via a pin or bolt or fastener 17 c. Plow wing connecting link 30 may beconnected to a rear portion or bracket or pin or axle 25 of therespective plow wing, and main plow connecting link 32 (or spaced apartconnecting links 32, such as shown in the illustrated embodiment) may beslidably connected to mounting portion 17 b, such as via a slottedopening 32 a and a pin, bolt or fastener or the like 17 d.

Each plow wing 16, 18 may be biased toward the forwardly angled positionvia at least one biasing member or element 36 (FIG. 2). In theillustrated embodiment, each of a pair of biasing members 36 includes aspring loaded rod or shaft which may extend along the rear portion ofmain plow 14 and may connect at its opposite ends to the rearwardmounting portion or pin or axle 25 of plow wings 16, 18. As shown inFIGS. 2 and 7, the spring loaded rod or biasing element 36 may include acylindrical rod portion 36 a and a spring loaded portion 36 b, whichbiases the rod portion 36 a toward an extended position or orientation,to bias or urge the plow wings toward their forwardly angled positionabout their respective pivot axles 24.

As can be seen with reference to FIGS. 4 and 6, pivotal movement ofcenter plow 14 about pivot axis 12 a may cause one of the cables 26 topull against one of the pivot arms 28, which in turn pulls against therear portion 25 of the respective plow wing via connecting link 30 topivot the plow wing relative to center plow 14 about its pivot axis 24and toward its generally aligned position. As pivot arm 28 is pulled bycable 26, the plow connecting link 32 may slide along a slotted openingwhich connects plow connecting link 32 to mounting portion 17 b ofcenter plow 14. The other cable 26 may slide outwardly relative to itsrespective pivot arm 28 to allow the other plow wing to remain in theforwardly angled position in response to biasing member or element 36.

Accordingly, when main or center plow 14 of plow assembly 10 ispositioned in its generally straight or non-angled orientation, such asshown in FIGS. and 4, biasing members 36 may apply or exert a biasingforce at plow wings 16, 18 to urge plow wings 16, 18 toward theirforwardly angled orientation about their pivot axes 24. The length ofcables 26, pivot arms 28 and connecting links 30, 32 may be selected andarranged such that when center plow 14 is in its generally straight ornon-angled position relative to support 12, cables 26 do not pullinwardly against either pivot arm 28, whereby both plow wings 16, 18 arein their fully forwardly angled position in response to biasing members36. As can be seen in FIG. 4, plow assembly 10 thus defines a generallyU-shaped plow, with both plow wings 16, 18 angled forwardly to theirangled positions.

When center plow 14 is angled or tilted toward one side or the other viaactuators 20 a, 20 b (such as shown in FIGS. 1, 5 and 6), forwardextending portion 12 c of support 12 pivots or moves toward the oppositeside of the plow assembly, such that forward extending portion 12 cpulls at cable 26 on the trailing side of center plow 14, which in turnpulls at pivot arm 28 to pivot the trailing plow wing (such as plow wing16 in FIGS. 1, 2, 5 and 6) toward its generally aligned position. Theother cable 26 may slide outwardly relative to the bushing 15 a atintermediate support 15 and relative to mounting arm 28, such that theopposite or leading plow wing (such as plow wing 18 in FIGS. 1, 2, 5,and 6) may remain angled towards its forwardly angled position.

Referring now to FIGS. 9 and 10, a plow assembly 11 includes a wingpivoting system or actuating system 22′, which is operable to pivot oneor both of the plow wings 16, 18 in response to pivoting of the centerplow 14 about the pivot axis 12 a. Plow assembly 10′ may besubstantially similar to plow assembly 10, discussed above, such that adetailed discussion of the plow assembly and components thereof will notbe repeated herein, The similar components are shown in the drawingswith the same reference numbers for both plow assemblies 10, 10′.Similar to plow assembly 10, when center plow 14 of plow assembly 10′ isin a generally straight or non-angled or center position, both plowwings 16, 18 may be positioned in or biased toward their forwardlyangled position, and when center plow 14 is angled toward one side ofthe vehicle, the plow wing that is toward the side of the vehicle orplow assembly toward which the center plow is angling (i.e. the trailingplow wing) may be pivoted to its generally aligned position ororientation in response to wing pivoting system 22′, while the otherplow wing (i.e. the leading plow wing) remains in its generallyforwardly angled position.

Plow wing pivoting system 22′ may include one or more cables 26′connected at forwardly extending portion 12 c of support 12 and movablein response to pivotal movement of center plow 14 about pivot axis 12 a,in order to pull a respective plow wing toward its aligned position.Cables 26′ may be pivotally mounted at forward extending portion 12 c ofsupport 12 and may extend laterally outwardly therefrom and through abushing or the like 15 a at intermediate support or bracket 15. An outerend 26 a′ of each cable 26′ may be slidably received through an outerend of a lever or pivot arm 28′ (or between spaced apart pivot arms 28′,as can be seen in FIG. 10). Pivot arm or arms 28′ may be pivotallymounted at a rear portion of main plow 14, such as via a pin, bolt orfastener 17 a′, and may extend generally rearwardly therefrom. As bestshown in FIG. 10, each pivot arm 28′ (such as each pair of spaced apartpivot arms) may be pivotally connected to a plow wing connecting link30′ (or pair of connecting links) via a pin or bolt or fastener 17 c′.Plow wing connecting link 30′ may be connected to a rear portion orbracket or pin 25′ of the respective plow wing 16, 18, which is offsetor spaced from the pivot axle or pin or axis 24 of the respective plowwing.

Each plow wing 16, 18 is biased toward its forwardly angled position viaat least one biasing member or device 36′. Optionally, and as shown inFIGS. 9-11, the biasing member may comprise a spring/damper device 36′which may extend along one side of the rear portion of center plow 14and may connect at one end 37 a to the center plow 14 (such as to abracket 27) and at its opposite end 37 b to the respective rearwardmounting portion or pin or axle 25′ of plow wings 16, 18. End 37 a maybe removably attached at the center plow 14 and may be selectivelyattached at different mounting locations along the center plow 14, suchas discussed below with respect to FIG. 14.

As shown in FIG. 11, each biasing device 36′ may include a rod portion36 a′, a biasing member or spring or spring element 36 b′ and an oilfilled cylinder 36 c′. The spring 36b′ biases the rod portion 36 a′toward an extended position or orientation to bias or urge the plow wingtoward its forwardly extending position about its respective pivot axle24. The oil filled cylinder or damper 36 c′ functions to control thespeed of the plow wing's return during extension or decompression of thebiasing device 36′. This may be accomplished via a check valve ororifice at a piston 36 d′ within cylinder 36 c′ that allows fluid withinthe cylinder 36 c′ to flow through the piston 36 d′ during compressionof the biasing device 36′ (which moves rod portion 36 a′ and piston 36d′ relative to cylinder 36 c′), but that restricts flow of fluid throughthe piston 36 d′ in the opposite direction or during decompression orextension of the biasing device 36′. Optionally, other types of biasingdevices or elements that may or may not provide such a dampeningfunction may be implemented, without affecting the scope of the presentinvention.

Similar to pivoting system 22, pivoting system 22′ utilizes a cable 26′to pull against a pivot arm 28′, which in turn pulls against the rearportion 25′ of the respective plow wing via connecting link 30′ to pivotthe plow wing about its pivot axis 24 and toward its generally alignedposition when the main or center plow is pivoted about its axis 12 a.The other cable 26′ may slide outwardly relative to its respective pivotarm 28′ to allow the other plow wing to move to or remain in theforwardly angled position in response to biasing member or element 36′.

The linkage geometry and/or cable lengths and/or cable mounting locationmay be selected to commence pivoting of the plow wing toward the alignedposition at a desired angle or degree of angling or triggerangle/position of the center plow, such that the plow wing may remain inits forward angled position until the center plow is angled or turned aparticular or predetermined or desired degree or angle toward eitherside of center. For example, the cables and/or linkage geometry may beselected so that the plow wings remain in their forwardly angledpositions until the center plow is angled approximately half of its fullangle capability toward either side. When the center plow reaches thedesired angle or trigger angle/position, the cable and linkage may beginpivoting the trailing plow wing and may pivot the plow wing toward itsgenerally aligned position as the center plow is angled further towardthat side (beyond the trigger angle). The linkage geometry may be set tocommence pivoting of the plow wing at the desired angle or trigger pointof the center plow and to provide full pivoting of the plow wing to itsgenerally aligned position during the remaining angling range of thecenter plow. It is further envisioned that the mounting location of thecables at the linkages and/or at the forwardly extending portion of thesupport may be adjusted (such as via selectively mounting or attachingthe cable at a selected one of two or more mounting openings or holes inthe linkages and/or forwardly extending portion) to adjust the triggerangle as may be desired depending on the particular application of theplow assembly.

Accordingly, when main or center plow 14 of plow assembly 10′ ispositioned in its generally straight or non-angled orientation, biasingmembers 36′ may apply or exert a biasing force at plow wings 16, 18 tourge plow wings 16, 18 toward their forwardly extending orientationabout their pivot axes 24. The lengths of cables 26′, pivot arms 28′ andconnecting links 30′ may be selected and arranged such that when centerplow 14 is in its generally straight or non-angled position relative tosupport 12, cables 26′ may not pull inwardly against either pivot arm28′, whereby both plow wings 16, 18 may be in their fully forwardlyangled position in response to biasing members 36′. When center plow 14is angled or tilted toward one side or the other via actuators 20 a, 20b, forward extending portion 12 c of support 12 pivots or moves towardthe opposite side of the plow assembly, such that forward extendingportion 12 c pulls at cable 26′ on the trailing side of center plow 14,which in turn pulls at pivot arm 28′ to pivot the trailing plow wing(such as plow wing 16 in FIGS. 9 and 10) toward its generally alignedposition. The other cable 26′ may slide outwardly relative to thebushing 15 a at intermediate support 15 and relative to mounting arm28′, such that the opposite or leading plow wing (such as plow wing 18in FIGS, 9 and 10) may remain angled towards its forwardly angledposition. When the center plow is pivoted back toward its centered ornon-angled position, the trailing plow wing may return to its forwardlyangled position, and may return in a controlled or dampened manner.

Therefore, the plow wing pivoting system of the present invention may beconfigured to pivot the trailing plow wing toward and to its generallyaligned position with respect to the main or center plow in response topivotal movement of the center plow toward that side, while maintainingthe leading plow wing in the forwardly angled position. It is furtherenvisioned that the length of cable 26 and the length and arrangement ofthe pivot arms 28 and connecting links 30, 32 may be selected such thatthe trailing plow wing may remain in its forwardly angled positionthrough much of the pivotal movement of the center plow, and may notpivot toward its generally aligned position until the center plowsubstantially angles or approaches or is substantially near anintermediate or trigger position or approaches or is substantially nearits fully angled position toward that side.

Optionally, a plow assembly 110 (FIG. 12), 110′ (FIG. 13) may include abiasing device 136, 136′, respectively, for biasing the plow wings 116,118 toward their forwardly angled positions. The biasing force orpressure exerted by the biasing device 136, 136′ may be overcome by aforce or load at one of the plow wings 116, 118 to pivot the plow wingto the aligned position. The force or load at the plow wing may beapplied when the plow assembly is plowing material and while the centerplow is angled at least partially toward the side of the respective plowwing, such that the trailing plow wing may pivot toward the alignedposition. For example, a force or load exerted against the plow wing ina direction generally along the main or center plow may overcome thebiasing force acting on the plow wing and may pivot or urge or push theplow wing toward its aligned position. The force may be from plowedmaterial moving along the center plow (either when in its centerposition or angled position) or from the plow wing striking an object asthe plow assembly is moved or driven by the vehicle,

In the illustrated embodiment of FIG. 12, biasing device 136 of plowassembly 110 comprises a pair of independent pressurized gas cylinders(one at each plow wing), which have pressurized gas within a head endportion 136 a of the cylinder, such that the piston rod 136 b of biasingdevice or cylinder 136 is biased outwardly toward an extended positionto pivot or urge the respective plow wing toward the angled position.When the force at the plow wing is great enough to overcome the biasingpressure within biasing device 136, piston rod 136 b may retract withinthe cylinder and compress the pressurized gas contained therein. Whenthe load is removed from the plow wing, the pressurized gas functions toextend the piston rod to bias and return the plow wing to the angledposition.

Optionally, as shown in FIG. 13, biasing device 136′ of plow assembly110′ may comprise one or more spring loaded rods, such as rods similarto the spring loaded rods 36 discussed above with respect to plowassembly 10. The biasing devices or rods may be connected between theopposite plow wings to bias or urge both of the plow wings toward theirforwardly angled positions. The biasing device 136′ thus biases bothplow wings 116, 118 toward their angled positions relative to the centerplow 114. When a sufficient force is applied to one of the wings, oneplow wing (such as the trailing wing when the center plow is angledtoward that side) may pivot toward its aligned position as the force mayovercome the biasing forces exerted by the biasing device. Because thebiasing device is connected between both plow wings, as one of the plowwings is pivoted toward its aligned position, the biasing force appliedto the other wing is increased to maintain the other plow wing in itsforwardly angled position. The biasing device 136′ thus may limit orsubstantially preclude pivoting of both plow wings toward their alignedpositions, because the biasing force acting on one plow wing 118 mayincrease when the other plow wing 116 (such as the trailing plow wing)has been pivoted toward or to its aligned position.

Although shown and described as pressurized cylinders and/or springloaded rods, it is envisioned that other biasing devices or members,such as springs or the like, may be implemented to bias one or both plowwings toward their angled positions relative to the center plow, withoutaffecting the scope of the present invention. Optionally, the plow wingsor biasing devices may be substantially locked when the main or centerplow is positioned generally at the center position or orientation, suchthat the plow wings may not pivot toward their aligned position untilthe center plow is pivoted or angled toward that side. Each wing orbiasing device may be mechanically latched or secured in its angledposition and then unlatched or released in response to movement orurging of the center plow at least partially toward or substantially toits fully angled position at that side.

Optionally, and with reference to FIG. 14, a plow assembly 110″ mayinclude a biasing/damping device 136″ to selectively position the wings116, 118 in either the aligned or forwardly angled positions relative tothe center plow 114. Biasing/damping device 136″ may be substantiallysimilar to biasing/damping device 36′, discussed above, such that adetailed discussion of the biasing/damping device will not be repeatedherein. One end 137 b of biasing/damping device 136″ may be pivotallymounted to the respective plow wing 116, 118, such as at a bracket 125.The other end 137 a of biasing/damping device 136″ may be selectivelymounted to center plow 114 via a pin 139. The plow wings 116, 118 may bepivotally attached to the ends of the center plow 114 and may bepivotable about a pivot axis 124. The bracket 125 may extend from or maybe attached to the respective plow wing 116. 118 and may be spaced fromthe pivot axis 124 of the plow wing, such that pivotal movement ofbracket 125 causes a corresponding pivotal movement o of plow wing 116,118 about pivot axis 124.

The end 137 a of each biasing/damping device 136″ may be positionedgenerally at one of two or more openings 139 a spaced along the main orcenter plow 114 (or along a bracket positioned at the rear of the centerplow or the like), such that the end 137 a may be selectively positionedalong the center plow 114. The pin 139 may be inserted through the end137 a and into the selected opening to mount the end 137 a of eachbiasing/damping device 136″ at the center plow. As can be seen in FIG.14, the selected location or hole at which end 137 a is positioned andmounted determines the angular orientation of the respective plow wing116, 118. For example, when the end 137 a of biasing/damping device 136″is mounted to a laterally outward hole at center plow 114, therespective plow wing is pivoted to its forwardly angled position, suchas shown with plow wing 118 in FIG. 14. Similarly, when end 137 a ofbiasing/damping device 136″ is mounted to the laterally inward hole atcenter plow 114, the respective plow wing is pivoted to its generallyaligned position, such as shown with plow wing 116 in FIG. 14.

The plow assembly 110″ thus provides a manually adjustable plow assemblywhere a user of the plow assembly may select which plow wing 116, 118 isto be angled forwardly and which is to be generally aligned, and mayattach the end 137 a of the biasing/damping devices 136″ to the centerplow in the appropriate manner. The biasing/damping devices 136″ thuspivot the plow wings and substantially retain the plow wings in thedesired orientation during operation and use of the plow assembly. Thespring 136 b″ provides a shock absorbing function for the plow wing ifthe plow wing encounters or impacts a large object or the like,particularly when the plow wing is in its forwardly angled position. Thedamping orifice (discussed above with respect to biasing/dampeningdevice 36′ of FIG. 11) may also control the decompression of the springand extension of the biasing/damping device and, thus, may control ordampen or slow the return of the plow wing to the forwardly angledposition after impacting the object. The plow assembly of the presentinvention thus provides for selective positioning of the plow wings andmay absorb the shock of the plow wings encountering substantially largeand/or immovable objects or bumps or the like.

Although shown as having two spaced apart openings to mount thebiasing/damping devices in one of two locations, it is envisioned thatmore than two openings or one or more slots may be provided toaccommodate different mounting locations for different positions of theplow wings, without affecting the scope of the present invention. Also,although shown and described as having two or more mounting Locations ator along the center or main plow, it is envisioned that the plow wing orwing bracket may provide two or more different mounting locations suchthat selective mounting or attaching of the biasing device to thedifferent mounting locations at the plow wing will position the plowwing in the desired or appropriate orientation relative to the centerplow, without affecting the scope of the present invention. Also,although shown and described as a biasing/damping device of the typedescribed above with respect to FIG. 11, the plow assembly may includeother types of biasing and/or shock absorbing devices or springs or thelike, such as the other types of cylinders or spring loaded rodsdiscussed herein, without affecting the scope of the present invention.

Referring now to FIGS. 15-19, a plow assembly 210 includes a pair ofplow wings 216, 218 positioned at opposite ends of a center or main plowor mold board 214. Each plow wing 216, 218 is pivotable between aforwardly angled position, such as plow wing 216 is shown in FIGS.15-19, and a generally aligned orientation, such as plow wing 218 isshown in FIGS. 5-19. Plow wings 216, 218 are pivotable between theirforwardly angled positions and generally aligned positions via a wingpivoting system or actuating system 222, which includes a pair ofactuators 222 a, 222 b operable to pivot the respective plow wings 216,218. Main or center plow 214 may be mounted to or connected to anintermediate support 215 in a similar manner as center plow 14 isconnected to intermediate support 15, discussed above. The intermediatesupport 215 may be pivotally mountable to a main support or A-framesupport or the like (not shown in FIGS. 15-19) and may be pivotablerelative to the main support and about a mounting pin 212 a, whichdefines a generally vertical pivot axis. The main support may bepivotally mountable to a push beam or the like of a vehicle, such as isknown in the art and/or in a similar manner as discussed above withrespect to plow assembly 10.

Similar to plow assembly 10, discussed above, center plow 214 of plowassembly 210 may include a main curved mold board or material engagingsurface 214 a and a plow blade 214 b (FIG. 19) for pushing or plowingsnow, dirt, sand, gravel and/or other plowable material as the centerplow 214 is moved through the snow or other material by the vehicle. Theplow wings 216, 218 also may each include a curved material engagingsurface or partial mold board 216 a, 218 a (FIG. 19) for pushing theplowed material as plow assembly 210 is moved through the material bythe vehicle. The partial mold boards 216 a, 218 a may partially overlapthe mold board 214 a of center plow 214, and may have curved inner edges216 b, 218 b (FIG. 19), such that center plow 214 and plow wings 216,218 maintain a generally uniform and continuous material engagingsurface irrespective of the position or orientation of either of theplow wings relative to the center plow. Each of the plow wings 216, 218may also include a plow blade 216 c, 218 c (FIG. 19) along the loweredge of the plow wings.

As best shown in FIGS. 16-18, plow wings 216, 218 are pivotally mountedto center plow 214 via a respective hinge or pivot pin 224. As best seenin FIG. 18, pin 224 extends generally vertically through a bracket 224 aat the respective outer end of center plow 214 and extends throughopenings 224 b in a bracket or flange 224 c at the inner end of therespective plow wing 216, 218. Actuators 222 a, 222 b are mounted at oneend 222 c to a bracket 217 at a rear portion of center plow 214 and/orintermediate support 215, and mounted at the other end 222 d to arespective mounting portion or pin 225 at bracket or flange 224 c of therespective plow wing 216, 218. Movement of the ends 222 d of actuators222 a, 222 b relative to center plow 214 thus causes pivotal movement ofthe respective plow wing 216, 218 about pin 224 to pivot the plow wingbetween the forwardly angled orientation and the generally alignedorientation with respect to the center or main plow.

In the illustrated embodiment, actuators 222 a, 222 b are hydrauliccylinders, which have a rod portion 223 a which is extendable andretractable relative to a cylinder portion 223 b in response topressurized hydraulic fluid being applied at either end of the cylinderportion. The piston rod 223 a of actuator 222 a, 222 b may be extendableand retractable relative to cylinder portion 223 b to pivot therespective plow wing 216, 218 relative to center plow 214. The pistonrod 223 a is movable within the cylinder portion 223 b and includes apiston which is slidable within the cylinder portion and divides thecylinder portion to define a laterally inward or head end portion 223 cof cylinder portion 223 b and a laterally outward or rod end portion 223d of cylinder portion 223 b at either side of the piston.

In the illustrated embodiment, the head end portion 223 c of cylinder223 b of each actuator 222 a, 222 b may be pressurized at a selectedpressure, such as via a fluid or gas contained within head end portion223 c of cylinder 223 b. The rod end portion 223 d of cylinder 223 b ofeach actuator 222 a, 222 b may be selectively pressurized via ahydraulic system (such as the hydraulic actuating system 200 of FIG. 20,discussed below) to retract piston rods 223 a into cylinder portions 223b, such that plow wings 216, 218 are pivoted toward their alignedpositions when the pressure within rod end portion 223 d is greater thanthe selected pressure within the head end portion 223 c of cylinders 223b. For example, the head end portion of each cylinder may be pressurizedwith a fluid or gas, such as, for example, nitrogen or other suitablegas or fluid, at a selected pressure, such as at an initial pressure ofapproximately 1,000 p.s.i. when the piston rod is extended therefrom, tobias or urge the piston rod toward its extended position, such that therespective plow wing is biased toward its forwardly angled position.Accordingly, in order to retract piston rod 223 a into cylinder portion223 b, hydraulic fluid of sufficient pressure may be applied to the rodend portion 223 d of cylinder portion 223 b (such as via respectivehydraulic fluid lines 221 in FIG. 20) to overcome the initial pressurewithin head end portion 223 c of cylinder portion 223 b. As the rod endpressure overcomes the head end or biasing pressure, the piston rod maymove towards it retracted position, thereby pivoting the plow wingtowards its generally aligned position, such as plow wing 218 is shownin FIGS. 15-19.

Plow wing pivoting system or actuating system 222 may be operable topivot the plow wings between their forwardly angled positions and theirgenerally aligned positions in response to selectively actuating aswitch or valve to pivot the center plow toward one side or the othervia a pair of plow angle actuators 220 a, 220 b (FIG. 20). The biasingpressure within the head end portion 223 c of the cylinder 223 b of eachplow wing actuator 222 a, 222 b functions to bias the actuator in itsextended position, which substantially retains the respective plow wingin its forwardly angled position. The biasing pressure may maintain therespective plow wing in its forwardly angled position until the pressurewithin the rod end portion of the cylinder overcomes the biasingpressure and thus retracts the piston rod and pivots the plow wing toits generally aligned position. The hydraulic actuating system 200 mayfunction to fully angle or pivot the center plow toward a selected sidebefore the pressure at the rod end portion of the actuator of thetrailing plow wing overcomes the biasing pressure within the head endportion of the actuator, as discussed below.

In the illustrated embodiment, and with reference to FIG. 20, rod endportions 223 d of cylinders 223 b of actuators 222 a, 222 b may be influid connection or communication with respective main plow anglingactuators 220 a, 220 b. Selective actuation of a solenoid valve orswitch may apply pressurized hydraulic fluid to fluid lines 221connected to or in fluid communication with actuators 222 a, 222 b and220 a, 220 b. Retraction of piston rod 223 a of right wing actuator 222b may thus be accomplished in response to pivotal movement of centerplow 214 toward the right side via actuation or extension of right angleactuator 220 a at the A-frame support or the like, while retraction ofleft wing actuator 222 a may be accomplished in response to pivotalmovement of center plow 214 toward the left side via actuation orextension of left angle actuator 220 b.

Optionally, the biasing pressure in the head end portions 223 d ofcylinder portions 223 b may be greater than the hydraulic pressurerequired to extend the respective plow angling actuator 220 a, 220 b topivot the center plow toward the right or left of the vehicle.Accordingly, the plow wings 216, 218 may be biased toward and may remainin their forwardly extended orientation relative to center plow 214until center plow 214 is at least substantially urged or angled towardone side or the other. As further fluid and/or pressure is applied tothe hydraulic lines 221, and as the actuators 220 a, 220 b may bottomout or fully extend/retract, the increased pressure in fluid lines 221may overcome the biasing pressure of the respective trailing wingactuator and may retract the piston rod 223 a to pivot the respectiveplow wing toward its generally aligned position. Optionally, theactuating system and plow assembly may be configured such that thepressure applied to the wing, actuator of the trailing plow wingincreases to the threshold amount to overcome the biasing pressure toretract the wing actuator in response to the main or center plow beingurged or angled a predetermined or selected amount between the centerposition and the fully angled position. The wing actuator may thenretract to pivot the trailing plow wing to its aligned position whilethe center plow may remain at the selected position. Further pressuremay then further urge or angle the center plow toward its fully angledposition.

As can be seen with reference to FIG. 20, if solenoid valve or switchsv1 of hydraulic actuating system 200 is energized, the right angle orleft side actuator or cylinder 220 a may extend (while the left angle orright side actuate 220 b may correspondingly retract) to pivot or anglethe center plow toward the right side of the vehicle, More particularly,when solenoid valve sv1 is energized, hydraulic fluid may be directed tothe right angle actuator or cylinder 220 a via a pilot operated checkvalve poc2 to extend actuator 220 a to angle the center plow toward theright side. Pressurized fluid may also be applied to a pilot operatedcheck valve poc4, but due to the biasing pressure or gas or fluid in thehead end portion 223 c of the right actuator or cylinder 222 b, thecenter plow 214 may angle toward the right side via extension ofactuator 220 a (and corresponding retraction of actuator 220 b), but theright wing actuator 222 b may generally remain extended and may notretract to pivot the right wing toward its aligned orientation inresponse to the pressurized fluid in the hydraulic system. However,after center plow 214 is substantially urged or angled toward the rightside, actuator 220 a and/or 220 b may bottom out and/or fullyextend/retract, whereby hydraulic pressure in the lines may buildup atcheck valves poc2 and poc4 until the pressure within the fluid line isgreater than or overcomes the biasing pressure or gas or fluid pressurewithin the head end portion of the right plow wing actuator 222 b,whereby the pressurized fluid may flow past the pilot operated checkvalve poc4 into the rod end portion 222 d of actuator 222 b to retractthe right wing actuator 222 b and to pivot the right plow wing 218 toits generally aligned position.

Angling in the other direction may work substantially similar to themanner described above, with the left plow wing remaining in itsforwardly angled position until the center plow is substantially fullyangled toward the left side, whereby the left plow wing may be pivotedto its generally aligned position. For example, a second switch orsolenoid valve sv2 may be actuated to provide pressurized hydraulicfluid to left angle or right side actuator 220 b and left wing actuator222 a via pilot operated check valves poc3 and poc1, respectively. Leftwing actuator 222 a may remain extended until the fluid pressure withinthe hydraulic lines overcomes the biasing pressure within the head endportion 223 c of left wing actuator 222 a.

Optionally, the hydraulic system 200 of FIG. 20 may also allow theoperator of the plow assembly to disengage the angle switch or valvesv1, sv2 to stop the angling of the main or center plow 214 toward therespective side just prior to the fully angled position of the centerplow, such that the trailing plow wing may remain in its forwardlyextended position, whereby the plow assembly may provide a generallyU-shaped plow even when angled substantially toward one side or theother, should such a plow configuration be desired. Optionally, pilotpressure from the pressurized hydraulic fluid line may be applied to thepilot operated check valve (poc1, poc4) associated with the actuator ofthe leading plow wing to open the check valve and allow hydraulic fluidto drain from the outer or rod end portion 223 d of the actuator 222 a,222 b of the leading plow wing, thereby allowing the actuator to besubstantially fully extended via the biasing or pressurized gas or fluidwithin the actuator to pivot or maintain the leading plow wing in itsforwardly angled position.

The present invention thus allows for substantial pivoting of the centerplow toward one side or the other, while the plow wings remain in theirforwardly angled orientations, and provides automatic pivoting of thetrailing plow wing to its generally aligned position in response to thecenter plow being at least substantially urged or pivoted or angledtoward that side. The plow wings thus may both be angled forwardlysubstantially throughout the full angling range of motion of the centerplow, whereby the trailing plow wing may pivot to its alignedorientation in response to the center plow pivoting to its fully angledposition or to a selected position between the center position and thefully angled position. This allows the center plow and plow wings tomaintain their generally U-shaped orientation throughout the anglingrange of motion of the center plow, which may be particularly suitablefor plowing snow or other material around a curve, because the trailingplow wing will remain angled forwardly to retain the material on theplow as the vehicle and plow assembly are driven around the curve.

As shown in FIG. 20, plow assembly 210 and hydraulic system 200 mayinclude a lift cylinder or actuator 240, which may be operable to raiseand lower the center plow relative to the vehicle via pivotal movementof the center plow and support about the generally horizontal axisdefined along the rearward end of the support, such as where the supportattaches to the push beam or the like of the vehicle. For example,actuation of a solenoid valve sv3 may extend actuator 240 to raise thecenter plow, while actuation of a solenoid valve sv4 may retractactuator 240 to lower the center plow, such as in a manner known in theart. Also, the hydraulic system 200 may include a cross port reliefvalve RV5 to allow either of the main plow angle actuators 220 a, 220 bto retract in response to excessive load occurring on one of the plowwings.

Therefore, the plow assembly of the present invention may provide agenerally U-shaped plow assembly during non-fully angled use ororientation of the center plow, while providing automatic pivoting ofthe trailing plow wing when the center plow is pivoted at leastpartially toward the respective side of the vehicle. Although shown anddescribed as having pressurized gas within the wing actuators to biasthe actuators toward their extended positions, it is envisioned thatother biasing elements or devices or members may be implemented, such asbiasing springs or other such elements, without affecting the scope ofthe present invention.

Referring now to FIG. 21, a hydraulic schematic of another hydraulicactuating system 300 is shown which may be operable to pivot or angle orurge the center plow toward one side or the other and to pivot or urgethe trailing plow wing to its generally aligned position when the centerplow is pivoted or urged at least substantially toward its fully angledposition or generally to a selected or predetermined position betweenthe center position and its fully angled position. When solenoid valveor switch S1 of hydraulic system 300 is energized, the right angle orleft side actuator or cylinder 320 a may extend (while the left angle orright side actuate 320 b may correspondingly retract) to pivot or anglethe center plow toward the right side of the vehicle. When solenoid S1is energized, hydraulic fluid may be directed to the right angleactuator or cylinder 320 a via a check valve CV1 to extend actuator 320a to angle the main plow toward the right side. When solenoid valve S1is actuated, a sequence valve SV2 may allow fluid to pass therethrough,as discussed below. Activation of solenoid valve S1 also providespressurized fluid to the rod end 323 d of right wing actuator 322 b atGenerally the same pressure as applied to actuator 320 a. However, thehead end portion 323 c of actuator 322 b is connected to or in fluidcommunication with the right side or left angle actuator 320 b viahydraulic fluid line 321. The pressure (P) in line 321 from retractionof actuator 320 k (which retracts as actuator 320 a is extended) is thengreater than the pressure (P/1.33 for a cylinder to rod ratio of 1.33for actuator 322 b) in the line from head end portion 323 c of actuator322 b. Therefore, actuator 322 b will not retract as the main plow ispivoted or angled toward the right side.

Sequence valve SV2 includes a pressure valve, such that fluid will notflow through the valve until the pressure in the fluid line overcomesthe pressure valve setting or threshold pressure or trigger pressure.For example, the pressure valve may keep the valve closed until thepressure in the line exceeds approximately 500 p.s.i. Therefore, leftangle actuator 320 b may not retract until the pressure in the fluidline 321 reaches that amount. When the pressure reaches that amount, theleft angle actuator 320 b may retract, causing the center plow to pivottoward the right side. The fluid will flow through the sequence valveSV2 and into the tank port of the solenoid valve S1. Although thepressure in fluid line 321 is sufficient to overcome the pressure valvesetting of the sequence valve SV1, the pressure in fluid line 321 isalso sufficient to limit or substantially preclude retraction of rightwing actuator 322 b while the center plow pivots to the right and, thus,while the left angle actuator 320 b retracts. When the center plow issubstantially fully angled or urged toward the right side, actuator 320a and/or 320 b may bottom out and/or fully extend/retract, such thatpressure at line 321 from left angle actuator 320 b will not increasefurther. The pressure applied through solenoid valve S1 thus mayincrease or buildup at rod end portion 323 d of right wing actuator 322b until it is sufficient to overcome the pressure in fluid line 321 andretract the right wing actuator 322 b to pivot the trailing or rightplow wing to its aligned position. Optionally, the hydraulic actuatingsystem may be configured to cause a pressure increase through solenoidvalve S1 in response to the plow actuator 320 a, 320 b reaching anotherposition before the fully extended/retracted position (and generallycorresponding to a selected or particular position of the center plowbetween the center position and the fully angled position), such thatthe wing actuator may be retracted in response to the center plow beingurged or angled toward the partially angled position between the centerposition and the fully angled position.

As can be seen in FIG. 21, the left plow wing actuator 322 a may bepressurized toward its extended state to pivot or maintain the left plowwing in its angled orientation in response to activation of solenoidvalve S1. Angling in the other direction may work substantially similarto the manner described above, with the left plow wing remaining in itsforwardly angled position until the center plow is substantially fullyangled toward the left side, whereby the left plow wing may be pivotedto its generally aligned position. For example, switch or solenoid valveS2 may be actuated to provide pressurized hydraulic fluid to left angleor right side actuator 320 b and left plow wing actuator 322 a. Leftplow wing actuator 322 a may remain extended until the fluid pressure atthe rod end portion 323 d of actuator 322 a overcomes the pressurewithin hydraulic line 321 as discussed above.

Similar to hydraulic system 200, discussed above, hydraulic system 300may include a lift cylinder or actuator 340, which may be operable toraise and lower the center plow relative to the vehicle via pivotalmovement of the center plow and support about the generally horizontalaxis defined along the rearward end of the support, such as where thesupport attaches to the push beam or the like of the vehicle. Forexample, actuation of a solenoid valve S3 may extend actuator 340 toraise the center plow, while actuation of a solenoid valve S5 mayretract actuator 340 to lower the center plow, such as in a manner knownin the art. Also, the hydraulic system 300 may include a cross portrelief valve RV3 to allow either of the main plow angle actuators 320 a,320 b to retract in response to excessive load occurring on one of theplow wings. Likewise, hydraulic system may include a relief valve RV1,RV4 at hydraulic lines 321 to provide pressure relief and allow arespective one of the plow wing actuators to retract in response to therespective plow wing encountering an object or the like which results inexcessive load or pressure at the head end portion of the plow wingactuator. The pressure valves RV1, RV4 require a greater pressure (suchas, for example, 1600 p.s.i.) than the pressure required to opensequence valves SV1, SV2, such that the relief valves RV1, RV4 may onlyopen in response to excessive pressure in the hydraulic fluid lines 321.

Referring now to FIG. 22, a hydraulic schematic of another hydraulicsystem 400 is shown which also may be operable to pivot or angle thecenter plow toward one side or the other and to pivot the trailing plowwing to its generally aligned position when the center plow is urged orpivoted at least substantially toward its fully angled position or to aposition between the center position and the fully angled position. Theplow wings thus may both be angled forwardly substantially throughoutthe full angling range of motion of the center plow, whereby thetrailing plow wing may pivot to its aligned orientation in response tothe center plow pivoting to its fully angled position.

With reference to FIG. 22, when solenoid valve or switch S1 of hydraulicsystem 400 is energized, pressurized fluid is applied to the head endportion 423 c of left wing actuator 422 a to extend the actuator andthus pivot the left plow wing to its forwardly angled position. Thefluid from the rod end portion 423 d of left wing actuator 422 a mayflow to the tank port of the solenoid switch or valve S1 via checkvalves CV1, CV2. After left wing actuator 422 a is fully extended orbottomed out, pressure will buildup at the inlet port of a sequencevalve SV1. Sequence valve SV1 may be activated to allow fluid to flowtherethrough when switch S1 is activated. Sequence valve SV1 includes arelief pressure valve, which restricts flow of fluid through the valveuntil the fluid is at a sufficient pressure, such as, for example,approximately 500 p.s.i. When the pressure in the fluid lines increasesto that level, pressurized fluid may be applied to the right angle orleft side actuator or cylinder 420 a to extend right angle actuator 420a (while the left angle or right side actuate 420 b correspondinglyretracts) to pivot or angle the center plow toward the right side of thevehicle. As right angle actuator 420 a extends, left angle actuator 420b retracts and fluid from left angle actuator 420 b may flow to the tankport of the system via check valve CV2.

As pressurized fluid is applied to right angle actuator 420 a,pressurized fluid is also applied to an inlet port of another sequencevalve SV3. The sequence valve SV3 may limit or restrict flowtherethrough until the fluid pressure at the inlet port reaches athreshold pressure (such as, for example, approximately 750 p.s.i.) thatis greater than the threshold pressure of sequence valve SV1. After themain plow is fully angled toward the right side, and right angleactuator 420 a is fully extended or bottomed out, the pressure appliedto the inlet port of sequence valve SV3 may increase to the thresholdpressure of sequence valve SV3 and fluid may flow through the valve andto the rod end portion 422 d of right wing actuator 422 b, therebycausing retraction of right wing actuator 422 b and pivoting of theright plow wing to its aligned orientation (the head end of the rightwing actuator may be in fluid communication with the tank port of thesolenoid switch or valve S1). Optionally, the plow assembly and/oractuating system may be configured such that the plow actuator 420 a,420 b may require additional pressure to extend further or retractfurther at a selected degree of extension or retraction or at a selectedposition of the center plow relative to the vehicle, such that thetrailing plow wing may be urged or pivoted toward the aligned positionin response to the main or center plow being urged or pivoted toward theselected or partially angled position between the center position andfully angled position.

As can be seen in FIG. 22, the left plow wing actuator 429 a may bepressurized toward its extended state to pivot or maintain the left plowwing in its angled orientation in response to activation of solenoidvalve S1. Angling in the other direction may work substantially similarto the manner described above, with the left plow wing remaining in itsforwardly angled position until the center plow is substantially fullyangled toward the left side, whereby the left plow wing may be pivotedto its generally aligned position. For example, switch or solenoid valveS2 may be actuated to provide pressurized hydraulic fluid to right wingactuator 422 b and then to left angle or right side actuator 420 b whenthe fluid pressure is sufficient to overcome the pressure valve settingof sequence valve SV2. While left angle actuator 420 b extends to pivotthe center plow toward the left side, left plow wing actuator 422 a mayremain extended until the fluid pressure at the inlet port of sequencevalve SV4 overcomes the threshold pressure setting of sequence valveSV4, as discussed above.

Similar to hydraulic systems 200, 300, discussed above, hydraulic system400 may include a lift cylinder or actuator 440, which may be operableto raise and lower the center plow relative to the vehicle via pivotalmovement of the center plow and support about the generally horizontalaxis defined along the rearward end of the support, such as where thesupport attaches to the push beam or the like of the vehicle. Forexample, actuation of a solenoid valve S3 may extend actuator 440 toraise the center plow, while actuation of a solenoid valve S5 mayretract actuator 440 to lower the center plow, such as in a manner knownin the art. Also, the hydraulic system 400 may include a cross portrelief valve RV3 to allow either of the center plow angle actuators 420a, 420 b to retract in response to excessive load occurring on one ofthe plow wings. Likewise, hydraulic system 400 may include a reliefvalve RV5 to provide pressure relief and allow a respective one of theplow wing actuators to retract in response to the respective plow wingencountering an object or the like which results in excessive load orpressure at the head end portion of the plow wing actuator.

Referring now to FIG. 23, a hydraulic schematic of another hydraulicactuating system 500 is shown which also may be operable to pivot orangle the center plow toward one side or the other and to pivot thetrailing plow wing to its generally aligned position when the centerplow is urged or pivoted at least substantially toward its fully angledposition or to a partially angled position between the center positionand the fully angled position. More particularly, when solenoid valve orswitch S1 of hydraulic system 500 is energized, pressurized fluid isapplied to the rod end portion 523 d of right wing actuator 522 b toapply pressure to retract the actuator and thus urge or pivot the rightplow wing to its aligned position. However, pressure in the head endportion 523 c of right wing actuator 522 b at least initially limits orsubstantially precludes retraction of the actuator, as discussed below.

When the switch S1 is actuated, pressurized fluid is also applied to theport of the left side or right angle plow actuator 520 a to pivot thecenter plow toward the right side. Pressurized fluid may also be appliedto the head end portion 523 c of left wing actuator 522 a via a checkvalve CV1 between plow actuator 520 a and left wing actuator 522 a, inorder to extend and maintain extension of the leading or left wingactuator 522 a to urge the left plow wing toward its forwardly angledposition.

As pressurized fluid is applied to right angle plow actuator 520 a, theactuator extends to pivot the center plow, which causes a correspondingretraction of the right side or left angle plow actuator 520 b. Theretraction causes fluid to be forced from the left angle plow actuator520 b to a tank port of the hydraulic system. When the left angle plowactuator 520 b has retracted a predetermined amount, such as at orsubstantially near bottoming out of the actuator, a check valve releasemechanism or device 521 may open the check valve CV2 between left angleplow actuator 520 b and right wing actuator 522 b. When the check valveCV2 opens, fluid may flow from right wing actuator 522 b through thecheck valve CV2 to the tank port, thereby allowing the pressurized fluidat the rod end portion 523 d of right wing actuator 522 b to retractright wing actuator 522 b to pivot the right plow wing toward itsaligned position.

Angling in the other direction may work substantially similar to themanner described above, with the left plow wing remaining in itsforwardly angled position until the center plow is at leastsubstantially angled toward the left side, whereby the left plow wingmay be pivoted to its generally aligned position. For example, switch orsolenoid valve S2 may be actuated to provide pressurized hydraulic fluidto left wing actuator 522 b and to left angle or right side actuator 520b in a similar manner as discussed above.

Optionally, and with reference to FIG. 24, the plow actuators 520 a, 520b may include the respective check valves CV1, CV2 and check valverelease mechanisms 521. In the illustrated embodiment of FIG. 24, thecheck valve CV1, CV2 is at a fluid port 525 a at the head end portion ofa cylinder 523 a of the actuator 520 a, 520 b. Check valve CV1, CV2 mayallow fluid to flow from the plow actuator, but will limit orsubstantially preclude fluid flow into the plow actuator when the checkvalve is closed. Check valve release mechanism 521 may comprise a rod orvalve member 521 a which may be movable between a closed position, wherea valve end at least substantially closes the fluid port 525 a, and anopened position, where the valve end is unseated and allows fluid toflow through the fluid port 525 a and into the plow actuator 520 a, 520b. As can be seen in FIG. 24, the rod portion 523 b of actuator 520 a,520 b may include a contact member 521 b for engaging valve member 521 aand moving valve member 521 a to the opened position as rod portion 523b is moved substantially to its bottoming out position relative tocylinder 523 a of actuator 520 a, 520 b. When check valve CV1, CV2 isopened, fluid may flow from the head end portion 522 c of the respectivewing actuator 522 a, 522 b through check valve CV1, CV2 into plowactuator 520 a, 520 b and out through the fluid port 525 b, whichconnects the actuator 520 a. 520 b to the pressure or tank ports of theactuating system via solenoid valves or switches S1, S2. The lengthand/or location of the valve member and check valve may be selected, orthe check valve or actuating system may otherwise be configured, toprovide release of the check valve at a desired amount of retraction ofthe actuator 520 a, 520 b, which corresponds to a desired amount ordegree of angling of the center plow between the center position and thefully angled position.

Hydraulic actuating system 500 may also include a relief valve or portRV1, RV2 which functions to allow fluid to flow from the head endportion 522 c of the respective wing actuator 522 a, 522 b when thecheck valve CV1, CV2 is not opened. For example, in situations where anexcessive load impacts the right plow wing, the pressure in the head endportion of the right wing actuator will increase as the plow wing ispushed toward its aligned position. When the pressure reaches athreshold level, such as, for example, approximately 1500 p.s.i., therelief valve RV1, RV2 may open to allow the fluid to flow from the headend portion of the wing actuator to the tank port of the actuatingsystem, thereby allowing the plow wing to be pivoted toward its alignedposition. Likewise, hydraulic system 500 may include a relief valve RV3to provide pressure relief and allow one of the plow actuators toretract in response to the plow encountering an object or the like whichresults in excessive load or force at one side of the plow. Similar tohydraulic systems 200, 300, 400, discussed above, hydraulic system 500may also include a lift cylinder or actuator 540, which may be operableto raise and lower the center plow relative to the vehicle via pivotalmovement of the center plow and support about the generally horizontalaxis defined along the rearward end of the support, such as where thesupport attaches to the push beam or the like of the vehicle. Similar tohydraulic system 200, discussed above, hydraulic systems 300, 400, 500may also allow the operator of the plow assembly to disengage the angleswitches S1, S2 to stop the angling of the center plow toward therespective side just prior to the fully angled position of the centerplow or prior to the selected or partially angled position between thecenter position and fully angled position of the center plow, such thatthe trailing plow wing may remain in its forwardly extended position,whereby the plow assembly may provide a generally U-shaped plow evenwhen angled at least partially toward one side or the other, should sucha plow configuration be desired.

The present invention thus allows for substantial urging or pivoting ofthe main or center plow toward one side or the other, while the plowwings may remain in their forwardly angled orientations, and providesautomatic pivoting of the trailing plow wing to its generally alignedposition in response to the center plow being at least substantially orfully pivoted or angled toward that side. The plow wings thus may bothbe angled forwardly substantially throughout the full or desired anglingrange of motion of the center plow, whereby the trailing plow wing maypivot to its aligned orientation in response to the center plow pivotingat least substantially to its filly angled position or to the partiallyangled position between the center position and the fully angledposition. This allows the center plow and plow wings to maintain theirgenerally U-shaped configuration throughout a desired angling range ofmotion of the center plow, which may be particularly suitable forplowing snow or other material around a curve, because the trailing plowwing will remain angled forwardly to retain the material on the plow asthe vehicle and plow assembly are driven around the curve. Althoughspecific examples of hydraulic actuating systems are shown and describedherein, it is envisioned that other types or configurations of actuatingsystems may be implemented to achieve the desired function, withoutaffecting the scope of the present invention.

Referring now to FIG. 25, a hydraulic schematic of another hydraulicactuating system 600 is shown. Hydraulic actuating system 600 may beoperable to automatically pivot the trailing plow wing toward and intoits aligned orientation as the main or center plow is angled or pivotedtoward that side. The actuating system may be configured such that thetrailing plow wing may pivot to and reach its fully aligned positionbefore the center plow pivots or angles toward that side. For example,the left plow wing may pivot toward and to its aligned position, andthen the center plow may angle all the way toward the left side inresponse to a switch or valve being actuated to pivot the center plowtoward the left side. Optionally, the hydraulic system may be operableto fully pivot the leading plow wing to its fully angled position beforepivoting the trailing plow wing to its aligned position, and thus beforeangling the center plow toward the trailing plow wing side, as discussedbelow.

More particularly, and with reference to FIG. 25, an operator may, forexample, activate the hydraulic system to pivot the center plow towardthe right side by actuating solenoid control valve S1. When solenoidvalve S1 is activated, pressurized hydraulic fluid may be provided to aninner or head end portion 623 c of a hydraulic cylinder 623 b of leftwing cylinder or actuator 622 a and to an outlet of a relief valve RV1.Because of the cylinder or piston ratio of actuator 622 a, the pressurein the rod end or outer end portion 623 d of cylinder 623 b is greaterthan the pressure in the head end portion 623 c of cylinder 623 b. Forexample, the pressure at the rod end portion 623 d may be approximately1.33 times the pressure at the head end portion 623 c (for a piston rodand piston assembly having a piston area that is approximately 1.33times the area of the piston less the rod diameter). Therefore, thefluid pressure at the inlet of relief valve RV1 is a greater pressurethan the pressure at the outlet of relief valve RV1. However, the reliefvalve RV1 will not open until the pressure applied at the inlet ofrelief valve RV1 is greater than the sum of the pressure at the outletend of the relief valve plus the relief valve pressure required to openthe relief valve when there is no pressure at the outlet end. Forexample, with a relief valve pressure or resistance of approximately 350p.s.i., the pressure in the hydraulic line from solenoid S1 at which therelief valve RV1 will open is approximately 1060 p.s.i. (p+350=1.33p).Accordingly, when the main line pressure reaches approximately 1060p.s.i., the relief valve RV1 may open and the left wing cylinder 622 amay extend to move the left wing to the fully angled position relativeto the center plow.

After the left wing actuator or cylinder 622 a is fully angledforwardly, the fluid pressure may increase in the hydraulic lines untilthe pressure is high enough to overcome the resistance or thresholdpressure in a relief valve RV2 (such as, for example, approximately 1250p.s.i.). When the pressure increases a sufficient amount, relief valveRV2 may open and the pressurized fluid may be applied to the left sideplow cylinder or the right angle plow cylinder or actuator 620 a.Because of the mechanical linkage between the plow cylinders 620 a, 620b, as the left plow cylinder 620 a extends to angle the center plow tothe right side, the right plow cylinder (or left angle cylinder) 620 bretracts, whereby fluid may exit the right plow cylinder 620 b and maypass through a check valve CV2 and into a rod end or outer end portion623 d of the cylinder portion 623 b of right wing cylinder or actuator622 b. Because the head end portion 623 c of cylinder 623 b of rightwing actuator 622 b may be connected to a tank port of the directionalsolenoid control valve S1, S2, piston rod 623 a of right wing cylinder622 b may retract to pivot the right plow wing toward and into itsaligned orientation relative to the center plow.

After the right plow wing is fully pivoted to its aligned orientationand/or actuator 622 b bottoms out, the pressurized fluid exiting fromthe right plow cylinder 620 b may overcome the resistance or thresholdpressure of a relief valve RV3, which may have a resistance ofapproximately 350 p.s.i., and may pass through relief valve RV3 to allowthe center plow to continue to angle toward the right side. Therefore,the center plow may not angle toward one side or the other until afterthe trailing plow wing is at least substantially urged or pivoted to itsaligned orientation. The operation of hydraulic system 600 issubstantially identical for pivoting the left plow wing to its alignedposition and pivoting the center plow toward the left side in responseto actuation of solenoid valve S2.

Additionally, hydraulic system 600 may provide a relief operation toallow the plow wing or center plow to pivot in response to one of theplow wings striking an immovable object. More particularly, an externalload at one of the plow wings may produce an increased pressure in therespective plow wing actuator and in the corresponding plow cylinder.For example, an external load at the end of the right plow wing mayproduce a pressure in the right side (or left angle) plow cylinder 620 bthat is approximately 2.12 times the load force at the right plow wing,while producing a pressure in the right wing actuator head end or innerend portion of approximately 1.68 times the load force at the right plowwing, due to the geometry of the plow and plow wings. Because the rightplow cylinder 620 b is in fluid communication with the rod end portionof the right plow wing actuator 622 b, the pressure in the right plowcylinder 620 b is additive to the right plow wing head end pressure.Therefore, the pressure in the right wing cylinder head end portion maybe approximately 3.27 times the force exerted at the end of the rightplow wing (1.68F+(2.12F/1.33)), based on the geometry of the plowassembly and on the cylinder ratio of the right plow wing actuator.

The pressure resistance at relief valve RV4 may be selected to avoidallowing fluid to overcome the relief valve RV4 during such a condition.Therefore, the pressure resistance at relief valve RV4 may be selectedto be approximately 1250 p.s.i., such that the pressure balance atrelief valve RV4 occurs at a force at the plow wing of approximately1083 pounds (2.12 F (the pressure at the discharge end of the reliefvalve)+1250=3.27 F). However, the relief valve RV5 may discharge to atank and may have a pressure resistance of approximately 2500 p.s.i.,such that the relief valve RV5 may open when the force at the plow wingis approximately 764 pounds or more (3.27 F=2500). Therefore, the rightwing actuator or cylinder may retract under a load of approximately 764pounds at the end of the right plow wing. After the right plow wingactuator bottoms out in its fully retracted orientation, the left anglecylinder 620 b may pass pressurized fluid through a relief valve RV6 toallow the center plow to pivot toward the right side. For example,relief valve RV6 may provide a pressure resistance or opening pressureof approximately 3500 p.s.i., such that left angle cylinder 520 b mayretract when the force at the right plow wing reaches approximately 1650pounds (2.12F-3500).

The hydraulic system may function in a substantially identical manner ifthe left plow wing strikes or engages a substantially immovable object.The hydraulic system of the present invention thus may allow each plowwing to pivot toward its aligned position and may further allow thecenter plow to pivot toward that side in response to the plow wingstriking or engaging an object with a sufficient force. It is noted thatthe values set forth above are exemplary values only, and other ratiosof forces and/or pressures may occur, depending on the geometry of theplow assembly, main or center plow, plow wings and/or cylinders oractuators and/or the like, without affecting the scope of the presentinvention.

As can be seen in FIG. 25, the plow assembly may include a lift cylinderor actuator 640, which may be operable to raise and lower the centerplow relative to the vehicle via pivotal movement of the center plow andsupport about the generally horizontal axis defined along the rearwardend of the support, such as where the support attaches to the push beamor the like of the vehicle. For example, actuation of a solenoid valveS3 may extend actuator 640 to raise the center plow, while actuation ofa solenoid valve S5 may retract actuator 640 to lower the center plow,such as in a manner known in the art.

The hydraulic system of the present invention thus may pivot thetrailing plow wing to its aligned position before angling the main orcenter plow toward that side. The hydraulic system may also providepressurized hydraulic fluid to the other or leading plow wing while thecenter plow is pivoting toward the trailing plow wing side. This mayprovide pressurized fluid to the leading plow wing actuator, so that ifthe leading plow wing strikes an object and is pushed back toward itsgenerally aligned position, the pressurized fluid may extend the leadingwing actuator to push the leading plow wing back to its forwardly angledposition as the center plow continues to pivot toward its angledposition on the other side. Pressurized fluid may also be provided tothe actuators of both plow wings to bias or urge the plow wings towardtheir forwardly angled position when the center plow is generally at itsstraight or non-angled orientation relative to the support, Although aspecific example of an actuating system is shown and described herein,it is envisioned that other types or configurations of actuating systemsmay be implemented to achieve the desired function, without affectingthe scope of the present invention.

Therefore, the present invention provides a plow assembly which includesa pair of plow wings which are biased or urged or initially angledtoward a forwardly angled position to define a generally U-shaped plowwhen the main or center plow is positioned in its generally straight ornon-angled position. The material engaging surfaces of the plow wingsand center plow may be curved, and the material engaging surfaces ormoldboards of the plow wings may partially overlap the material engagingsurface or mold board of the center plow to provide a generally uniformand continuous surface. The plow wings may have curved inner edges, suchthat the center plow and the plow wings maintain a generally uniform andcontinuous material engaging surface irrespective of the position ororientation of either of the plow wings relative to the center plow. Theplow wings may be pivotally mounted at the ends of the center plow viarespective hinges that may be positioned Generally rearward of thematerial engaging surfaces of the plow wings and the center plow so asto provide a substantially continuous plow surface throughout the rangeof pivotal adjustment of the plow wing or wings relative to the main orcenter plow.

The plow assembly of the present invention provides for pivotal movementof a trailing plow wing as the center plow is angled toward that side ofthe vehicle. The plow wing may be maintained in its forwardly angledposition at least partially or substantially throughout the range ofangling motion of the center plow, and then may be pivoted to itsgenerally aligned position in response to the center plow reaching thefully or partially angled position or a trigger position or angle thatis toward that side. The plow wings may be biased toward their forwardlyangled positions to substantially preclude angling of the plow wingstoward their aligned positions until the center plow is fully angledtoward one side or the other of the vehicle or until the center plow ispartially angled a desired amount toward one side or the other.Optionally, the plow assembly of the present invention may be operableto pivot the plow wings to their generally aligned position prior toangling the center plow toward either side. The plow wings may bepivoted or moved between their forwardly angled position and generallyaligned position via a hydraulic actuating system or via a mechanicalactuating system, such as via cables and lever arms and the like, or viaany other actuating means or systems or biasing devices or elements orthe like. The trailing plow wing may be pivoted toward its alignedposition in response to the center plow being pivoted to and beyond aparticular position or angle or trigger position/angle or the plow wingmay pivot toward its aligned position in response to a trigger pressurein the fluid lines that overcomes a pressure valve setting.

Changes and modifications in the specifically described embodiments maybe carried out without departing from the principles of the presentinvention, which is intended to be limited only by the scope of theappended claims, as interpreted according to the principles of patentlaw.

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 28. A plow assembly for avehicle, said plow assembly comprising: a center plow having first andsecond ends, said center plow being mountable to the vehicle and beingpivotable relative to the vehicle between a first position, where saidcenter plow is pivoted toward said first end, and a center position,where said center plow is positioned generally normal to the directionof travel of the vehicle; a first plow wing pivotally mounted at saidfirst end of said center plow, said first plow wing being pivotablebetween an angled position, where said first plow wing is angledforwardly with respect to said center plow, and an aligned position,where said first plow wing is generally aligned with said center plow;and an actuating system operable to urge said first plow wing towardsaid angled position until said center plow is urged at leastsubstantially toward one of said first position and a position betweensaid first and center positions, said actuating system urging said firstplow wing toward said aligned position in response to said center plowbeing urged at least substantially toward said one of said firstposition and a position between said first and center positions.
 29. Theplow assembly of claim 28, wherein said actuating system is operable tourge said first plow wing toward said aligned position in response tosaid center plow being urged at least substantially toward said firstposition.
 30. The plow assembly of claim 29, wherein said actuatingsystem is operable to urge said first plow wing toward said angledposition in response to said center plow being at least partially urgedtoward a second position, where said center plow is pivoted toward saidsecond end.
 31. The plow assembly of claim 29, wherein said first plowwing is biased toward said angled position such that said first plowwing is generally in said angled position when said center plow ispositioned generally at said center position or generally between saidfirst and center positions.
 32. The plow assembly of claim 28, whereinsaid actuating system includes a first wing actuator operable to urgesaid first plow wing toward said aligned position.
 33. The plow assemblyof claim 32, wherein said actuating system includes at least one plowactuator operable to pivot said center plow between said first andcenter positions.
 34. The plow assembly of claim 33, wherein saidactuators are responsive to pressurized fluid.
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